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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 34  |  Issue : 3  |  Page : 183-188

The effectiveness of piriformis injection under fluoroscopy and nerve stimulator guidance with local anaesthetic and steroid for management of piriformis syndrome among manual workers in Eastern India: A prospective interventional study


1 Department of Pain Management, Guest Faculty, ESI Institute of Pain Management; Department of Pain and Palliative Care, Chittaranjan National Cancer Institute, Kolkata, West Bengal, India
2 Department of Pain Management, ESI Institute of Pain Management, Kolkata, West Bengal, India
3 Department of Pain Management, Guest Faculty, ESI Institute of Pain Management, Kolkata, West Bengal, India
4 Department of Pain Management, Guest Faculty, ESI Institute of Pain Management, Kolkata; Department of Community Medicine, Raiganj Government Medical College, Raiganj, West Bengal, India

Date of Submission05-Jun-2020
Date of Decision18-Jul-2020
Date of Acceptance05-Sep-2020
Date of Web Publication28-Dec-2020

Correspondence Address:
Dr. Subrata Goswami
Flat No 10, Doctors' Block, 3 A/1 MS Road, Kolkata - 700 009, West Bengal
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijpn.ijpn_76_20

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  Abstract 


Background: Piriformis syndrome (PS) is a neuromuscular disorder characterized by compression or irritation of sciatic nerve by the piriformis muscle causing pain, tingling, and numbness in the buttocks and sometimes along the distribution of the sciatic nerve descending down to the leg. Pharmacotherapy and physical-therapy remain the first line of management. Local anesthetic (LA) with steroid injection in piriformis muscle is given if conservative management fails. Nerve stimulator, electromyography, radiological imaging, and various other methods have been used to increase the reliability of injections. In the present study, the efficacy of combined fluoroscopy and nerve stimulator guided piriformis injection with LA and steroid for the management of PS has been re-validated among the manual workers of Eastern India. Subjects and Methods: With ethical permission and informed consent from 35 patients of PS fulfilling the inclusion and exclusion criteria were given piriformis injection with 5 mL of 0.25% bupivacaine and 20 mg methyl prednisolone under guidance of a combination of fluoroscopy and nerve stimulator. Thirty-one patients completed the study. Pain in Numeric Rating Scale and Disability by Ronald Morris Disability Questionnaire were recorded for all patients before the procedure, 1 h, 1 week, 3 weeks, and 12 weeks after the procedure and were statistically analyzed. Results: Pain score and back disability score decreased significantly (P < 0.05) after the injection, and the effect was also sustained up to 12 weeks. Conclusions: Injection of LA along with steroid in piriformis muscle under fluoroscopy and nerve stimulator guidance, followed by physiotherapy, is an effective treatment for PS among manual workers.

Keywords: Fluoroscopy and nerve stimulator guided injection, local anesthetic, low back pain, piriformis injection, piriformis syndrome, steroid


How to cite this article:
Jatua D, Sarkar B, Nandi G, Bhandari B, Karmakar PR, Goswami S, Basu SM. The effectiveness of piriformis injection under fluoroscopy and nerve stimulator guidance with local anaesthetic and steroid for management of piriformis syndrome among manual workers in Eastern India: A prospective interventional study. Indian J Pain 2020;34:183-8

How to cite this URL:
Jatua D, Sarkar B, Nandi G, Bhandari B, Karmakar PR, Goswami S, Basu SM. The effectiveness of piriformis injection under fluoroscopy and nerve stimulator guidance with local anaesthetic and steroid for management of piriformis syndrome among manual workers in Eastern India: A prospective interventional study. Indian J Pain [serial online] 2020 [cited 2021 Jan 22];34:183-8. Available from: https://www.indianjpain.org/text.asp?2020/34/3/183/305149




  Introduction Top


Piriformis syndrome (PS) is a neuromuscular pain condition characterized by compression over the sciatic nerve by the piriformis muscle mostly due to trauma-related inflammation followed by hypertrophy.[1] It comprises 5%–6% of patients who are being referred for treatment of low back pain and leg pain.[2] The compression over the sciatic nerve causes pain, tingling and numbness in the buttocks and sometimes descending down into the thigh and leg along the distribution of the sciatic nerve. The pain worsens with prolonged sitting, especially sitting on a hard surface or when standing up from a sitting posture.[3] In physical examination, three signs are most important for the diagnosis of PS. (1) Pace sign: pain and weakness on resisted abduction of the hip while patient's hip is flexed. (2) Freiberg's sign: pain on forced internal rotation of the extended thigh and (3) Flexion adduction and internal rotation (FAIR) test: pain aggravated by hip flexion, adduction and internal rotation.[4] Although the diagnosis of PS predominantly depends on clinical grounds, imaging modalities such as computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography and other modalities like electromyography (EMG) or nerve conduction studies may aid the diagnosis.[5]

The treatment of PS starts with conservative pharmacotherapy, including nonsteroidal anti-inflammatory drugs (NSAIDs), muscle relaxants, neuropathic agents and continues with physical therapy, including stretching of the piriformis muscle.[3],[4],[6] When conservative regimen fails, injection of local anesthetic with steroid can be given in piriformis muscle to relieve the patient's pain.[7],[8] Nerve stimulator techniques, EMG, fluoroscopy, CT, MRI and ultrasound have been described as guide for infiltration in the piriformis muscle.[6],[9],[10],[11] Fluoroscopy and nerve stimulator are easily available in our country, and a combination of these two modalities can place the needle in a more accurate position.[12] Due to work-related repetitive trauma, low back pain along with PS is quite prevalent in manual workers in India.[13] Though there are few studies worldwide, no study could be found by the authors done on the manual worker population about the efficacy of piriformis injection with local anesthetics (LAs) with corticosteroid (CS) using combination of fluoroscopy and nerve stimulator.[12]

Aims and objectives of the study

The primary objective of the study was to assess the pain relief in numerical rating scale (NRS) score after piriformis injection under fluoroscopic and nerve stimulator guidance with LA plus CS in PS among manual workers in Eastern India. Assessing the improvement in functional disability was the secondary objective of the study.

Endpoints

Pain relief was assessed at one hour, one week, three weeks and 12 weeks after the procedure, and functional improvement was assessed at one week, three weeks and 12 weeks after the procedure. Follow-up was done up to 12 weeks after the procedure.


  Subjects and Methods Top


Selection and description of the participants

After obtaining approval from the Institutional Ethics Committee, this present study was registered in the clinical trial registry of India (CTRI/2017/08/0099223). With informed consent from each patient (n = 35), all the patients, who were manual workers of both sex, aged 18–70 years coming to the out-patient department of a tertiary referral pain clinic from February 2017 to July 2017, who had the unilateral hip and/or leg pain with the positive FAIR test, positive pace sign and/or Freiberg's sign; tenderness and/or trigger point at piriformis muscle; who had pain in NRS score > 6 even after conservative therapy such as pharmacotherapy (including NSAIDs, muscle relaxants and anti-neuropathic medicines), physical therapy (stretching exercises) at least for 4 weeks, and who had > 50% short-term pain relief after diagnostic pirifromis injection with lignocaine, were included in the study. Those patients who had neurological deficiency, uncontrolled severe systemic illnesses like hypertension, diabetes mellitus, coagulopathies, infectious or inflammatory diseases, vascular/tumoral disease, history of allergy to LA or contrast agent were excluded from the study.

Study design

The present study was a prospective, single-arm, interventional study. All the patients (n = 35) included in the study, according to inclusion and exclusion criteria, received piriformis injection after the initial assessment. Follow-up of the patients was done at one hour, one week, three weeks and 12 weeks after the procedure. Patients who did not complete follow-up to 12 weeks were withdrawn from the study. Any complications regarding the procedure like intravascular injection, infection, nerve injury, motor weakness or numbness were noted.

Preprocedure assessment

All the patients were assessed by two criteria:

  1. Pain: It was recorded by the NRS score. The patient had to report in an 11-point scale (0 to 10) according to the intensity of pain, where 0 means no pain and 10 means the worst imaginable pain[14]
  2. Disability: It was recorded by the Roland Morris Disability Questionnaire (RMDQ) [Annexure 1]. It is a self-administered disability measure by the patients where a greater level of disability is reflected by higher scores in 24-point scale (maximum disability 24 and no disability 0).[15]


Description of the injection procedure

The procedures were done in an operation theatre (OT) having all resuscitative equipment and drugs. After taking informed consent from the patients, they were taken to OT and were asked to lie in a prone position. Intravenous (IV) cannulation was done, and IV fluid (0.9% Normal Saline) started very slowly. All the monitors for pulse oximetry, blood pressure and electrocardiograph were attached. Draping from mid-back to mid-thigh area was done in sterile manner. Anterior-posterior view of the pelvis, acetabulum, and greater trochanter of the affected side was obtained. The most inferior aspect of the sacroiliac joint was identified as medial landmark, whereas greater trochanter was the lateral landmark. The point of entry of the needle was the midpoint of the imaginary line connecting those two landmarks.[16] The superficial skin was anesthetized with 2% lignocaine infiltration. A 15 cm long insulated nerve stimulator needle, connected to a nerve stimulator is inserted and advanced in tunnel vision with the X-ray beams. Initially, the stimulation output was fixed at 1.5–2.0 milliamps and 2 hz frequency,[9],[12] and the muscle twitching confirmed the needle position in the gluteus maximus muscle. The needle was further introduced gradually till only flickering of the hub obtained confirming the needle tip crossed beyond the gluteus muscle level. Occasionally if the needle touched the bone, it was withdrawn 2–3 mm till the hub started flickering. The output was reduced to 0.6–0.8 amp and the needle tip was adjusted until there was the flickering of the needle hub only, which suggested that the needle tip position probably was inside the piriformis muscle. Any paresthesia or contractions of calf muscles or foot muscles were checked. If found any, the needle tip was repositioned to avoid proximity to the sciatic nerve[12] [Figure 1]. 1–2 mL nonionic dye was injected into the muscle through the air freed catheter attached to the needle. After confirming the sausage-shaped outline of the piriformis muscle in fluoroscopic image, 5 mL of 0.25% bupivacaine with 20 mg depot preparation of Methyl prednisolone was injected into the muscle gradually after repetitive negative aspirations [Figure 2]. Washing out of dye was confirmed by fluoroscopy and the needle was taken out. Patients were instructed to take oral Ibuprofen 400 mg one tablet thrice daily for the first 3 days after procedure to combat the procedural pain and continue the anti-neuropathic medicines (Gabapentin, Amitriptyline) as before. They were also instructed to continue the stretching exercises after 72 h following the procedure.
Figure 1: Procedure with nerve stimulator needle in situ inside operation theater

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Figure 2: Fluoroscopic image of dye deposition with nerve stimulator needle

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Post procedure assessment

Post-procedure NRS score was assessed at one hour, one week, three weeks and 12 weeks after the procedure (NRS-1 h, NRS-1 week, NRS-3 weeks, NRS-12 weeks), whereas the RMDQ score was recorded at one week, three weeks and 12 weeks after the procedure (RMDQ-1 week, RMDQ-3 weeks, and RMDQ-12 weeks). Total of 31 patients (n = 31) completed the follow-up to 12 weeks.

Statistical analysis

For those patients who completed follow up (n = 31), the reduction in NRS score and RMDQ score was statistically analyzed by IBM SPSS Statistics software, version 22 (New York, USA). As the data were nonparametric data, and there were repeated measurements, the Friedman test followed by Wilcoxon Signed-Ranked test was used for statistical evaluation. Value of P < 0.05 was taken to be statistically significant.


  Results Top


One patient developed bladder bowel incontinence 5 days after the procedure. Posterocentral disc prolapsed at L4–L5 level with cauda equina compression was found in MRI. He was urgently transferred to Neurosurgery Department and excluded from the study. One patient did not come back for follow-up at 3 weeks, while two more patients did not come back for follow-up at 12 weeks after the procedure. Excluding the loss of follow-up (n = 4), the analysis of the data for the rest of the patients (n = 31) were done [Figure 3].
Figure 3: Flow chart of the study

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General description of the patients

Among 31 patients, 21 patients were male (67.74%) and 10 patients were female (32.26%). The mean age with the standard deviation of the patients was 45.50 ± 9.38 years, with a range of 24–67 years.

Nineteen patients (61.2%) had a history of trauma in the gluteal region. Fifteen patients (48.3%) gave a history of sitting for prolonged periods or bad sitting habits, while 13 patients (61.9% of the male patients) used to carry wallet in the rear pocket in the affected side.

Comparison of pain and functional disability before and after piriformis injection:

  1. Pain: From the values of NRS score in different times, Friedman test was applied, and it showed that the pain scores reduced significantly with time up to 12 weeks (Chi-square: 72.587, P < 0.001). Wilcoxon Signed-Ranks test showed that pain score was significantly lower at 1 h after injection, at 1 week, 3 weeks, and 12 weeks after injection as compared to pain score before injection [Table 1]. It was also seen that there was no significant difference between NRS score at 1 h after injection compared to at 1 week after injection (P = 0.425), similarly between NRS at 1 week and 3 weeks after injection (P = 0.334). At 12 weeks after injection NRS scores reduced significantly when compared to NRS score at 3 weeks after injection (P = 0.002) [Figure 4]
  2. Disability: From Friedman's test summary with the values of RMDQ scores with different times, it was seen that there was significant decrease in the RMDQ score after the intervention. The Chi-square value was 84.448 and P < 0.001 [Figure 5]. Wilcoxon Signed-Ranks test showed significant decrement of RMDQ score even at 1 week after injection and that decrement persisted at 3 weeks and 12 weeks after injection.(P < 0.05) [Table 2].
Table 1: Wilcoxon Signed-rank test statistics for Numeric Rating Scale score

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Figure 4: Bar diagram showing mean pain score in the numerical rating scale at before injection and 1 h, 1 week, 3 weeks, and 12 weeks after injection

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Figure 5: Bar diagram showing mean disability in Roland Morris disability questionnaire score at before injection and 1 h, 1 week, 3 weeks, and 12 weeks after injection

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Table 2: Wilcoxon signed-rank test statistics for Ronald Morris Disability Questionnaire score

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  Discussion Top


The diagnosis of PS is controversial due to lack of any gold standard diagnostic method. Some authors described PS as an under-diagnosed condition[17],[18] while other have described it as an over diagnosed condition.[19] Though ultrasound, CT, MRI,[20] EMG,[21] more recently, ultrasound elastography[22] and scoring system[23] have been used, the positive response after diagnostic piriformis injection with LA is the most widely accepted method to diagnose PS.[5],[12],[19] The detailed history taking, careful clinical examination followed by diagnostic block with lignocaine has been done for diagnosis before the recruitment of patients in the present study.

In the present study, one patient developed bladder bowel incontinence 5 days after the procedure. Posterocentral disc prolapsed at L4–L5 level with cauda equine compression was found in MRI. Early screening with MRI of the lumbosacral spine before going for piriformis injection may be helpful to avoid this type of situation.[24]

The age group of the patients of our study (45.50 ± 9.38 years) is similar to the previous literature showing that it is most common in between 40 and 60 years of age.[25]

Male: Female ratio was 2.1:1, which is in contrast to 1:6, found in the literature.[26] Probably this contrast is due to male dominance among manual workers in our society. No significant difference in the effect of piriformis injection between males and females was found in the present study.

In the present study, the history of trauma in the gluteal region (61.2%) is a little higher than expected (50%) as per literature,[25],[26],[27] probably because of higher rates of accidents and work-related trauma inside the mills. A similar history pattern of sitting for prolonged periods or bad sitting habits and carrying wallet in the rear pocket in the affected side was found in previous studies.[6]

Regarding the injection technique, many techniques have been described in the literature. Previously blind injections were given with the help of anatomical landmarks.[26] With the advances in technology, fluoroscopy, ultrasound, CT or MRI, electromyogram, nerve stimulator guided injection have made the blinded injection obsolete.[6],[9],[10],[11] A combination of nerve stimulator with fluoroscopy or ultrasound has been successfully used with more precise needle placement.[12],[28] Although ultrasonography with no radiation exposure has been described superior than fluoroscopy by some authors,[11] still now fluoroscopy-guided injection is more commonly being practiced in India probably due to easy availability of fluoroscope and its cost-effectiveness. In the present study, we used a nerve stimulator under fluoroscopy guidance. The injection was given inside the intramuscular belly of piriformis muscle, which is the most common site of injection found in the literature.[4]

In this study, combination of CS and LA was injected. This combination is most commonly used in the literature.[7] It has been seen that these drugs reduce inflammation, swelling around the nerve, ectopic discharge from the nerves and also fasten the recovery of nerve conduction.[8] Misirlioglu et al. used only LA and found no significant difference with LA and CS combination.[6]

In the present study, 31 patients were given piriformis injection followed up to 3 months by NRS score (for pain) and RMDQ score (disability). The NRS and RMDQ score reduced significantly after the injection. All the patients were advised to continue stretching exercise of the piriformis. This observation is supported by the other literatures, which state, the effect of piriformis injection along with continued physiotherapy stays even up to 12 weeks after injection.[6] The pain reduction was significant at 1 h after injection, probably due to the effect of LA. After that, pain reduced very slowly but steadily as there was no significant difference between NRS score at 1 h after injection compared to at 1 week after injection, similarly between NRS at 1 week and 3 weeks after injection. This slow but steady reduction of pain was probably due to the effect of slowly releasing steroids from the depot preparation followed by exercise. Surgery (dissecting, reducing the volume of piriformis muscle) should be considered if all other methods fail or in the presence of anatomical abnormality.[29]

A total volume of 5 mL of LA with CS was used in the present study for injection. Only four patients complained of temporary numbness with weakness immediately after the injection. All of them were managed by careful observation only. Drug volume may be reduced especially in patients with less adipose tissue to reduce this incidence, as suggested by Hanania and Kitain.[8] No other side effect or complication was noted during this study.

Hence, this study further validates the use of LA (Bupivacaine) and CS (Methyl prednisolone), followed by physiotherapy as an effective method of treatment in manual workers suffering from PS. Patients can do stretching exercises in home after pain reduction. It reduces the number of visits to designated physiotherapy centers and ultimately reduces the cost of treatment and facilitates the manual workers for early return to work.

Limitations: The present study has some limitations as follows:

  1. It is an open level single-arm trial without any control group. Blinded randomized controlled trial is necessary to understand whether the effect was only due to LA or CS or combination of LA and CS or due to the needling procedure itself
  2. The requirement of NSAIDs and muscle relaxants was not documented and calculated though from our experience, it can be said the requirement of those drugs reduced dramatically
  3. No patient satisfaction score was used in this present study.



  Conclusions Top


The combined fluoroscopy and nerve stimulator-guided piriformis injection is a safe, reliable procedure for the management of PS. Piriformis injection with LA plus CS, followed by physiotherapy, can reduce the pain and disability effectively for at least 12 weeks among the manual workers suffering from PS.

Acknowledgment

We sincerely acknowledge the help from Director, ESI-MB Scheme, Dr. Aditi Das, Director, ESI Institute of Pain Management, and Superintendent, Sealdah ESI Hospital, for their help and necessary permission for conducting the study. We are grateful to Dr. Amit Chackraborty, Director, ICMR-ROHC, Kolkata. We are really thankful to all the staff and colleagues of EIPM without whose support the study would not have been completed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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[PUBMED]  [Full text]  
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2]



 

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